Part 2 :
There was a special optimization on the ref access method for
ORDER BY ... DESC that was set without actually looking on the type of the
selected index for ORDER BY.
Fixed the SELECT ... ORDER BY .. DESC (it uses a different code path compared
to the ASC that has been fixed with the previous fix).
There are three issues that caused rpl_killed_ddl fails sporadically
in pb2:
1) thd->clear_error() was not called before create Query event
if operation is executed successfully.
2) DATABASE d2 might do exist because the statement to CREATE or
ALTER it was killed
3) because of bug 43353, kill the query that do DROP FUNCTION or
DROP PROCEDURE can result in SP not found
This patch fixed all above issues by:
1) Called thd->clear_error() if the operation succeeded.
2) Add IF EXISTS to the DROP DATABASE d2 statement
3) Temporarily disabled testing DROP FUNCTION/PROCEDURE IF EXISTS.
field='const1' AND field='const2' in some cases
Building multiple equality predicates containing
a constant which is compared as a datetime (with a field)
we should take this fact into account and compare the
constant with another possible constatns as datetimes
as well.
E.g. for the
SELECT ... WHERE a='2001-01-01' AND a='2001-01-01 00:00:00'
we should compare '2001-01-01' with '2001-01-01 00:00:00' as
datetimes but not as strings.
Actually there is two different bugs.
The first one caused crash on queries with WHERE condition over views
containing WHERE condition. A wrong check for prepared statement phase led
to items for view fields being allocated in the execution memory and freed
at the end of execution. Thus the optimized WHERE condition refers to
unallocated memory on the second execution and server crashed.
The second one caused by the Item_cond::compile function not saving changes
it made to the item tree. Thus on the next execution changes weren't
reverted and server crashed on dereferencing of unallocated space.
The new helper function called is_stmt_prepare_or_first_stmt_execute
is added to the Query_arena class.
The find_field_in_view function now uses
is_stmt_prepare_or_first_stmt_execute() to check whether
newly created view items should be freed at the end of the query execution.
The Item_cond::compile function now saves changes it makes to item tree.
BUG#46000 - using index called GEN_CLUST_INDEX crashes server
Detailed revision comments:
r6180 | jyang | 2009-11-17 10:54:57 +0200 (Tue, 17 Nov 2009) | 7 lines
branches/5.0: Merge/Port fix for bug #46000 from branches/5.1
-r5895 to branches/5.0. Disallow creating index with the
name of "GEN_CLUST_INDEX" which is reserved for the default
system primary index. Minor adjusts on table name screening
format for added tests.
BUG#47777 - innodb dies with spatial pk: Failing assertion: buf <= original_buf + buf_len
Detailed revision comments:
r6178 | jyang | 2009-11-17 08:52:11 +0200 (Tue, 17 Nov 2009) | 6 lines
branches/5.0: Merge fix for bug #47777 from branches/5.1 -r6045
to bracnches/5.0. Treat the Geometry data same as Binary BLOB
in ha_innobase::store_key_val_for_row(), since the Geometry
data is stored as Binary BLOB in Innodb.
WHERE conditions
check_group_min_max() checks if the loose index scan
optimization is applicable for a given WHERE condition, that is
if the MIN/MAX attribute participates only in range predicates
comparing the corresponding field with constants.
The problem was that it considered the whole predicate suitable
for the loose index scan optimization as soon as it encountered
a constant as a predicate argument. This is obviously wrong for
cases when a constant is the first argument of a predicate
which does not satisfy the above condition.
Fixed check_group_min_max() so that all arguments of the input
predicate are considered to decide if it passes the test, even
though a constant has already been encountered.
memory
The server was doing a bad class typecast causing setting of
wrong value for the maximum number of items in an internal
structure used in equality propagation.
Fixed by not doing the wrong typecast and asserting the type
of the Item where it should be done.
values
We should re-set the access method functions when changing the access
method when switching to another index to avoid sorting.
Fixed by doing a little re-engineering : encapsulating all the function
assignment into a special function and calling it when flipping the
indexes.
only const tables
The problem was caused by two shortcuts in the optimizer that
are inapplicable in the ROLLUP case.
Normally in a case when only const tables are involved in a
query, DISTINCT clause can be safely optimized away since there
may be only one row produced by the join. Similarly, we don't
need to create a temporary table to resolve DISTINCT/GROUP
BY/ORDER BY. Both of these are inapplicable when the WITH
ROLLUP modifier is present.
Fixed by disabling the said optimizations for the WITH ROLLUP
case.
Bug#41756 "Strange error messages about locks from InnoDB".
In JT_EQ_REF (join_read_key()) access method,
don't try to unlock rows in the handler, unless certain that
a) they were locked
b) they are not used.
Unlocking of rows is done by the logic of the nested join loop,
and is unaware of the possible caching that the access method may
have. This could lead to double unlocking, when a row
was unlocked first after reading into the cache, and then
when taken from cache, as well as to unlocking of rows which
were actually used (but taken from cache).
Delegate part of the unlocking logic to the access method,
and in JT_EQ_REF count how many times a record was actually
used in the join. Unlock it only if it's usage count is 0.
Implemented review comments.
When a sessione is closed, all temporary tables of the session are automatically
dropped and are binlogged. But it will be binlogged with wrong database names when
the length of the temporary tables' database names are greater than the
length of the current database name or the current database is not set.
Query_log_event's db_len is forgot to set when Query_log_event's db is set.
This patch wrote code to set db_len immediately after db has set.
with temporary tables
There were two problems the test case from this bug was
triggering:
1. JOIN::rollup_init() was supposed to wrap all constant Items
into another object for queries with the WITH ROLLUP modifier
to ensure they are never considered as constants and therefore
are written into temporary tables if the optimizer chooses to
employ them for DISTINCT/GROUP BY handling.
However, JOIN::rollup_init() was called before
make_join_statistics(), so Items corresponding to fields in
const tables could not be handled as intended, which was
causing all kinds of problems later in the query execution. In
particular, create_tmp_table() assumed all constant items
except "hidden" ones to be removed earlier by remove_const()
which led to improperly initialized Field objects for the
temporary table being created. This is what was causing crashes
and valgrind errors in storage engines.
2. Even when the above problem had been fixed, the query from
the test case produced incorrect results due to some
DISTINCT/GROUP BY optimizations being performed by the
optimizer that are inapplicable in the WITH ROLLUP case.
Fixed by disabling inapplicable DISTINCT/GROUP BY optimizations
when the WITH ROLLUP modifier is present, and splitting the
const-wrapping part of JOIN::rollup_init() into a separate
method which is now invoked after make_join_statistics() when
the const tables are already known.
subquery returning multiple rows
Error handling was missing when handling subqueires in WHERE
and when assigning a SELECT result to a @variable.
This caused crash(es).
Fixed by adding error handling code to both the WHERE
condition evaluation and to assignment to an @variable.
having clause...
The fix for bug 46184 was not very complete. It was not covering
views using temporary tables and multiple tables in a FROM clause.
Fixed by reverting the fix for 46184 and making a more general
check that is checking at the right execution stage and for all
of the non-supported cases.
Now PROCEDURE ANALYZE on non-top level SELECT is also forbidden.
Updated the analyse.test and subselect.test accordingly.
Queries with nested outer joins may lead to crashes or
bad results because an internal data structure is not handled
correctly.
The optimizer uses bitmaps of nested JOINs to determine
if certain table can be placed at a certain place in the
JOIN order.
It does maintain a bitmap describing in which JOINs
last placed table is nested.
When it puts a table it makes sure the bit of every JOIN that
contains the table in question is set (because JOINs can be nested).
It does that by recursively setting the bit for the next enclosing
JOIN when this is the first table in the JOIN and recursively
resetting the bit if it's the last table in the JOIN.
When it removes a table from the join order it should do the
opposite : recursively unset the bit if it's the only remaining
table in this join and and recursively set the bit if it's removing
the last table of a JOIN.
There was an error in how the bits was set for the upper levels :
when removing a table it was setting the bit for all the enclosing
nested JOINs even if there were more tables left in the current JOIN
(which practically means that the upper nested JOINs were not affected).
Fixed by stopping the recursion at the relevant level.
Problem 1:
column_priv_hash uses utf8_general_ci collation
for the key comparison. The key consists of user name,
db name and table name. Thus user with privileges on table t1
is able to perform the same operation on T1
(the similar situation with user name & db name, see acl_cache).
So collation which is used for column_priv_hash and acl_cache
should be case sensitive.
The fix:
replace system_charset_info with my_charset_utf8_bin for
column_priv_hash and acl_cache
Problem 2:
The same situation with proc_priv_hash, func_priv_hash,
the only difference is that Routine name is case insensitive.
So the fix is to use my_charset_utf8_bin for
proc_priv_hash & func_priv_hash and convert routine name into lower
case before writing the element into the hash and
before looking up the key.
Additional fix: mysql.procs_priv Routine_name field collation
is changed to utf8_general_ci.
It's necessary for REVOKE command
(to find a field by routine hash element values).
Note:
It's safe for lower-case-table-names mode too because
db name & table name are converted into lower case
(see GRANT_NAME::GRANT_NAME).
If the first argument to GeomFromWKB function is a geometry
field then the function just returns its value.
However in doing so it's not preserving first argument's
null_value flag and this causes unexpected null value to
be returned to the calling function.
Fixed by updating the null_value of the GeomFromWKB function
in such cases (and all other cases that return a NULL e.g.
because of not enough memory for the return buffer).
Problem: involving a spatial index for "non-spatial" queries
(that don't containt MBRXXX() functions) may lead to failed assert.
Fix: don't use spatial indexes in such cases.
line 138 when forcing a spatial index
Problem: "Spatial indexes can be involved in the search
for queries that use a function such as MBRContains()
or MBRWithin() in the WHERE clause".
Using spatial indexes for JOINs with =, <=> etc.
predicates is incorrect.
Fix: disable spatial indexes for such queries.
grants are reapplied.
After renaming a user and trying to re-apply grants results in additional
grants.
This is because we use username as part of the key for GRANT_TABLE structure.
When the user is renamed, we only change the username stored and the hash key
still contains the old user name and this results in the extra privileges
Fixed by rebuilding the hash key and updating the column_priv_hash structure
when the user is renamed
If a thread is killed in the server, we throw "shutdown" only if one is actually in
progress; otherwise, we throw "query interrupted".
Control-C in the mysql command-line client is "incremental" now.
First Control-C sends KILL QUERY (when connected to 5.0+ server, otherwise, see next)
Next Control-C sends KILL CONNECTION
Next Control-C aborts client.
As the first two steps only pertain to an existing query,
Control-C will abort the client right away if no query is running.
client will give more detailed/consistent feedback on Control-C now.
can lead to bad memory access
Problem: Field_bit is the only field which returns INT_RESULT
and doesn't have unsigned flag. As it's not a descendant of the
Field_num, so using ((Field_num *) field_bit)->unsigned_flag may lead
to unpredictable results.
Fix: check the field type before casting.
On Mac OS X or Windows, sending a SIGHUP to the server or a
asynchronous flush (triggered by flush_time), would cause the
server to crash.
The problem was that a hook used to detach client API handles
wasn't prepared to handle cases where the thread does not have
a associated session.
The solution is to verify whether the thread has a associated
session before trying to detach a handle.
The 'BEGIN/COMMIT/ROLLBACK' log event could be filtered out if the
database is not selected by --database option of mysqlbinlog command.
This can result in problem if there are some statements in the
transaction are not filtered out.
To fix the problem, mysqlbinlog will output 'BEGIN/ROLLBACK/COMMIT'
in regardless of the database filtering rules.
query
The fix for bug 46749 removed the check for OUTER_REF_TABLE_BIT
and substituted it for a check on the presence of
Item_ident::depended_from.
Removing it altogether was wrong : OUTER_REF_TABLE_BIT should
still be checked in addition to depended_from (because it's not
set in all cases and doesn't contradict to the check of depended_from).
Fixed by returning the old condition back as a compliment to the
new one.
The problem is that argument buffer can be used as result buffer
and it leads to argument value change.
The fix is to use 'old buffer' as result buffer only
if first argument is not constant item.
function,file sql_base.cc
When uncacheable queries are written to a temp table the optimizer must
preserve the original JOIN structure, because it is re-using the JOIN
structure to read from the resulting temporary table.
This was done only for uncacheable sub-queries.
But top level queries can also benefit from this mechanism, specially if
they're using index access and need a reset.
Fixed by not limiting the saving of JOIN structure to subqueries
exclusively.
Added a new test file to extend the existing (large) subquery.test.
name as existing view
When trying to create a table with the same name as existing view with
join, mysql server crashes.
The problem is when create table is issued with the same name as view, while
verifying with the existing tables, we assume that base table object is
created always.
In this case, since it is a view over multiple tables, we don't have the
mysql derived table object.
Fixed the logic which checks if there is an existing table to not to assume
that table object is created when the base table is view over multiple
tables.
field references
This error requires a combination of factors :
1. An "impossible where" in the outermost SELECT
2. An aggregate in the outermost SELECT
3. A correlated subquery with a WHERE clause that includes an outer
field reference as a top level WHERE sargable predicate
When JOIN::optimize detects an "impossible WHERE" it will bail out
without doing the rest of the work and initializations. It will not
call make_join_statistics() as well. And make_join_statistics fills
in various structures for each table referenced.
When processing the result of the "impossible WHERE" the query must
send a single row of data if there are aggregate functions in it.
In this case the server marks all the aggregates as having received
no rows and calls the relevant Item::val_xxx() method on the SELECT
list. However if this SELECT list happens to contain a correlated
subquery this subquery is evaluated in a normal evaluation mode.
And if this correlated subquery has a reference to a field from the
outermost "impossible where" SELECT the add_key_fields will mistakenly
consider the outer field reference as a "local" field reference when
looking for sargable predicates.
But since the SELECT where the outer field reference refers to is not
completely initialized due to the "impossible WHERE" in this level
we'll get a NULL pointer reference.
Fixed by making a better condition for discovering if a field is "local"
to the SELECT level being processed.
It's not enough to look for OUTER_REF_TABLE_BIT in this case since
for outer references to constant tables the Item_field::used_tables()
will return 0 regardless of whether the field reference is from the
local SELECT or not.
When a connection is dropped any remaining temporary table is also automatically
dropped and the SQL statement of this operation is written to the binary log in
order to drop such tables on the slave and keep the slave in sync. Specifically,
the current code base creates the following type of statement:
DROP /*!40005 TEMPORARY */ TABLE IF EXISTS `db`.`table`;
Unfortunately, appending the database to the table name in this manner circumvents
the replicate-rewrite-db option (and any options that check the current database).
To solve the issue, we started writing the statement to the binary as follows:
use `db`; DROP /*!40005 TEMPORARY */ TABLE IF EXISTS `table`;
The crash happens because select_union object is used as result set
for queries which have derived tables.
select_union use temporary table as data storage and if
fields count exceeds 10(count of values for procedure ANALYSE())
then we get a crash on fill_record() function.
